M51

Continuing studies of Canon T1i camera, this time mounted at Cassegrain focus of a 10-in LX-200 telescope (2,500mm ) at Broemmelsiek Observatory.

On Wednesday night, 2 March 2011 I pointed the telescope with camera attached to M51 which was reasonably high in the NE sky.  First, I had focused the camera using a Bahtinov mask on Regulus.  After a few test shots to center the galaxy in the fov (more-or-less), I commenced a series of 60 15-sec exposures (15 sec is about the limit of non-trailing stars without guiding).  Camera settings were for "S" size and ISO of 1600.  All images were saved as JPEGs.

 Deep Sky Stacker found 53 of the images to its liking so the final image represents about 13 min 15 sec of exposure.  The only processing was with the curves adjustment in DS S.  The TIF image from DSS was imported into MaximDL where it was binned 3x3 and the data range was stretched to 8 bit and saved as a JPEG.  The JPEG image was cropped in Gimp to 480x360 as shown below.  No flat field correction nor dark current subtraction.

 

For comparison to another camera, on March 10, 2010 I used the club's SBIG STL-1001 camera (with Paracorr) on the C-14 at Broemmelsiek Park (4309 mm).  This camera is a research-grade monochrome camera nicely matched to the long focal length of the C-14.  Still experimenting with how long a sub-exposure can be taken without guiding but the two following examples are stacks 12 sub-frames of 15 and 30 seconds, respectively.  Dark and flat correction, stacked in MaximDL.  16 bit stretch followed by a log-normal stretch and conversion to 8-bit for the final JPEG image in MaximDL.  Click image for full size.

12x15sec

12x30 sec



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